A working state of a computer comprises a normal state (S0 state), a sleep state (S3 state), and a dormant state (S4 state), the computer is at full speed when in the S0 state. A first power supply circuit is not enough to supply power to a peripheral card (such as a network card or a display card) of the computer when the computer is in the S0 state. A first power supply and a second power supply circuit are too much for the peripheral card when the computer is in the S0 state. No power supply circuit supplies power to the addition card when the computer is in the S0 state.